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Volume 48, Issue 3
Displaying 1-16 of 16 articles from this issue
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Katsutoshi KAWABE, Kenji KATO, Johnson KIMURA2000 Volume 48 Issue 3 Pages 467-473
Published: September 20, 2000
Released on J-STAGE: January 31, 2011
JOURNAL FREE ACCESSIn the periods from 1986 to 1998, spawning of broodstock of blacktip grouper, Epinephelus fasciatus, obtained from coastal waters around Chichi-jima, one of the Ogasawara Islands, was observed under the rearing condition. No artificial treatments such as hormonal injection, water temperature shock, or photoperiod shock was performed to induce maturation. Although year round spawning was observed, about 90% of the eggs were obtained from April to November, when water temperature varied between 19.5 and 29.7°C . The average diameter of the buoyant eggs ranged from 717 to 847μm and significantly showed a negative correlation with spawning water temperature. The number of spawning eggs peaked a few days after full moon.View full abstractDownload PDF (1177K) -
Shigeru MIYASHITA, Osamu MURATA, Yoshihumi SAWADA, Tokihiko OKADA, Yos ...2000 Volume 48 Issue 3 Pages 475-488
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSWild young bluefin tuna, Thunnus thynnus, caught in 1987, were cultured up to be adults. From 5 years old, presumably the fish became mature, the seasonal change of their gonado-somatic index (GSI) was examined. From June to August every year, their spawning condition was observed. In addition, the gonad condition was examined during the spawning season, and the microstructure of the sperm and egg was observed. Cultured bluefin tuna naturally spawned from 7 years old. The observed bluefin tuna spawned 4 years out of 8 years examined. GSI reached the maximum in July. The spawning season was mid June to mid August when water temperature ranged from 21.6 to 29.2°C, the required temperature for hatching. A female of 7 years old had mature eggs although its size was small (21.3 kg body weight). The size composition of eggs in ovary showed multple frequency peaks. There were more than 25% of eggs larger than 0.8 mm in diameter. Multiple spawning of bluefin tuna in one season was observed in the present study.
The spermatozoa of Thunnus thynnus are 35μm in total length, and are composed of head, middle piece, and tail, which are the typical form of Teleostei. A micropyle was observed on the chorion at the position where is supposed to be the animal pole. Numerous pits were observed on the whole chorion.View full abstractDownload PDF (10494K) -
Yasuhiko TAGO, Ryo TSUJIMOTO, Shigeru MATSUSHIMA, Shuichi AZUMA, Taiji ...2000 Volume 48 Issue 3 Pages 489-495
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSRearing of juveniles of the masu salmon, Oncorhynchus masou, in a side-channel excavated inside a river reservation was conducted in the Jinzu River from April to October during 1995 to 1997. The side-channel was 157 m long, 5-6 m wide and 0.6-1.2 m deep. The number of juveniles reared initially was 200 thousands (2.9 g in average body weight), 570 thousands (0.7 g) and 230 thousands (4.1 g) each year. Juveniles grew up to 16.7 g, 17.1 g and 15.2 g in body weight as of October of each year. Fork length, body weight and condition factors of juveniles reared in the side-channel were larger than those reared in the Jinzu Hatchery as of the month of October. Many juveniles fed on terrestrial insects that fell on the surface of the water in addition to artificial foods. The returning rate of marked juveniles released from the channel into the Jinzu River was estimated to be 0.24% in 1997, and this rate was almost equal to those released as fingerlings and smolts which were reared and released from the Jinzu hatchery from 1990 to 1995. It is considered that rearing masu salomon juveniles in side-channels inside river reservation is one of the most effective ways to propagate a masu salmon resource.View full abstractDownload PDF (3239K) -
Hiroshi MIZUTANI, Seiichi MATSUI, Naohiko TAKESHITA2000 Volume 48 Issue 3 Pages 497-502
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSThe embryonic, larval and juvenile development of an anadromous salangid fish, Salanx ariakensis, is described on the basis of a series of laboratory-reared and wild specimens. The eggs were colorless, adhesive, demersal, and slightly elliptic without any oil globules. Mean diameter of the eggs was 0.94 mm in the major axis and 0.89 mm in the minor axis. Hatching occurred 8 days after fertilization in water at a temperature of 15.5-20.1°C. Newly-hatched larvae, measuring 4.7±0.2 mm in notochord length (NL) (mean±SD, n=15), had 53-54+18-19=71-73 myomeres. The yolk-sac extended from below the pectoral fin to the anus, and was nearly absorbed 2 days after hatching at 6.4±0.2 mm NL (n=15). Notochord flexion was completed by 23.5 mm in standard length (SL). Caudal, anal and dorsal fin rays were fully developed by approximately 23.5 mm SL. In a wild specimen, pectoral and pelvic fin rays and adipose fin were completed by approximately 44.1 mm SL. Completion of fin development occurred in the following sequence: caudal, anal, dorsal and finally pectoral and pelvic fin.
Larvae and juveniles of S. ariakensis differ from those of confamilial species in having 53-54 preanal myomeres and a dorsal fin base extending above the center of the anal fin base (vs. 44-46 and above the origin of the anal fin in Salangichthys microdon; and 36 and above the anus in Neosalanx regani).View full abstractDownload PDF (864K) -
Masatoshi BAN2000 Volume 48 Issue 3 Pages 503-508
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSJuvenile chum salmon, Oncorhynchus keta, were reared under various feeding conditions for three years. In 1992, fry which emerged in March were fed at 4% of body weight a day. In 1995, fry which emerged in February (95-a-class) and in March (95-b-class) were fed at 1% of body weight a day. In 1996, fry which emerged in February were fed at 3% of body weight a day. The instantaneous growth rate of the 92-class and the 96-class reached 0.0045 in March and February, respectively, followed by a decline below 0.0040. The 95-a-class and the 95-b-class stayed less than 0.0029 in their instantaneous growth rate throughout the experimental period. Significant differences in growth rate were observed between the 92-class and the 95-b-class in March, and between the 95-a-class and the 96-class in February. The gill Na+, K+ ATPase activity of the 92-class and 96-class increased and peaked in May and June, respectively. However, both 95-a-class and 95-b-class did not show distinct increases in this enzyme activity. These results indicate that high growth for the first month after emergence may be a prerequisite for expressing gill Na+, K+-ATPase of juvenile chum salmon.View full abstractDownload PDF (837K) -
Ken-ichi YAMAMOTO, Masakazu KONDO, Takeshi HANDA, Masatoshi NAKAMURA2000 Volume 48 Issue 3 Pages 509-516
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSTo evaluate the effect of ozone-produced oxidants (OPO) on the ventilation of the pearl oyster, Pinctada fucata martensii, the ventilation volume (Vg), the gill cilia movement (SP) and observation of the surface structure of gills were examined after exposure to ozonated seawater for 24 hr. Vg was examined every 3 hr during exposure to the seawater of OPO 0.70 mgO3/l. Also the day when Vg recovered to the level of the control after exposure (DY) was examined. In the 24 hr, Vg and SP decreased with an increase in the OPO concentration, and showed zero at 0.58 mgO3/l or more. DY was under 23 days at 0.42 mgO3/l or below, and 10-80 days at 0.58-0.70 mgO3/l. However at 0.58-0.70 mgO3/l, 20 % of the individuals used for the experiment died 5-76 days later. Every 3 hr, Vg decreased with time. DY was under 23 days within 12 hr and 25-80 days at 24 hr. From the observation, the damages of the gills were postulated to progress in order that the frontal cilia dispappeared, the lateral cilia dispappeared, the ciliary disc collapsed, and the gill filaments disappeared from the tip.View full abstractDownload PDF (7450K) -
Yoshiyuki TAKAYA, Kenji KAWAMATA2000 Volume 48 Issue 3 Pages 517-522
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSIn order to determine the optimal release size of seedlings of barfin flounder, Veyasper moseri, the starvation resistance was examined at three developmental stages.
During the starvation experiment, 50% mortality of the 50mm size group and the 80mm size group occurred by the 63rd day and 112th day, respectively. None of the 100mm size group died during the 120 days of the starvation experiment. These results indicate that seedlings of Barfin flounder can survive relatively long-term starvation and that larger sizes have higher survival rates.
Morphometric changes in the condition factor (CF) and hepatopancreas somatic index (HSI) showed similar patterns; both values decreased significantly after 2 days of starvation for the 50mm and 80mm size groups. For the 100mm size group, the CF value decreased significantly after 10 days and the HSI value decreased significantly after 50 days.
Significant decreases in the biochemical composition (protein, RNA/DNA and glycogen) in the youngest group were found on the second day of starvation. Although the RNA/DNA ratio of the 100mm size group decreased significantly on the 5th day of starvation, the protein and glycogen contents did not change throughout the experimental period. In the 80mm size group, the protein content did not decrease during the experiment, but the RNA/DNA ratio decreased significantly on the 5th day similar to the 100mm size group. Glycogen decreased on the second day as found in the 50mm size group.
Judging from the changes in the biochemical composition, the higher survival rate in the larger size group may be due to a restraint mechanism of energy expenditure, which is developed in older juveniles.View full abstractDownload PDF (877K) -
Shusaku TAKAGI, Sadao SHIMENO, Hidetsuyo HOSOKAWA, Masaharu UKAWA2000 Volume 48 Issue 3 Pages 523-530
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSThe replacement of fish meal (FM) by inclusion of soybean meal (SBM), corn gluten meal (CGM) and poultry by-product meal (PBM) in juvenile red sea bream, Pagrus major diet was investigated.
Juvenile fish weighing 8.3 g on average were fed for 60 days with the test diets: (1)0-39%SBM, (2)24%SBM and 10-20%CGM, (3)24%SBM and 13-26%PBM, (4)24%SBM, 10-20%CGM and 13-26%PBM.
Palatability of test diets were not affected by the dietary treatment at all. The growth performance was not affected by dietary inclusion of up to 39%SBM (replacing of 50%FM). The best performance was observed in fish fed the diet containing 24%SBM and 13%PBM (replacing 50%FM). The per-formance of the diets containing 24%SBM and 10%CGM with or without 13%PBM (replacing of 50% and 70%FM) were similar to that of the control diet which contained 50%FM. Feed conversion of these dietary groups were similar to or slightly lower than that of the control group. The performance, however, became significantly poorer with further increase of CGM or PBM content in diet.
These results indicated that 50%FM in juvenile red sea bream diet could be replaced by inclusion of either 24%SBM and 10%CGM or 24%SBM and 13%PBM. In addition, 70%FM could be replaced by inclusion of these three alternative protein sources without amino acid supplementation.View full abstractDownload PDF (1316K) -
Masaya NIIRO, Hachiro HIRATA2000 Volume 48 Issue 3 Pages 531-536
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSIn order to know the effects of probiotic additive feedings in culture of carp, two feeding trials were conducted. In trial 1, 2% and 5% of Uchishiro microorganisms (UM) were added to the mash diets, respectively. In trial 2, 2% and 5% of commercial yogurts (CY) were added, respectively. In each trial, sterilized UM and CY were added to the diets as“control”. Algal growth potential (AGP), fecal total nitrogen (TN), fecal remaining rate (FRR), and water quality were determined; nitrogen (DIN), phosphate (DIP), pO2, and pCO2 were used as indicators for evaluating water quality.
In both trials, higher AGP, about 120%, lower DIN, lower DIP and lower pCO2 were obtained in the culture water of carp fed on the diets containing UM and CY. Thus, negative correlationship between AGP and DIN, DIP, pCO2 was indicated. This way due to the metabolism of the algae, N. oculata grown in the culture water. Furthermore, lower TN and FRR were obtained at the trials containing UM and CY.
Those results suggested that adding probiotic additives to the diets can mitigate the self pollution in aquaculture.View full abstractDownload PDF (816K) -
Kotaro KIKUCHI, Haruo SUGITA, Takeshi WATANABE2000 Volume 48 Issue 3 Pages 537-543
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSSix extruded diets with dietary protein levels of 45 and 55% and three lipid levels each were formulated to examine the effect of dietary protein and lipid levels on growth and body composition of Japanese flounder. Japanese flounder of about 55 g initial body weight were fed the diets to apparent satiation twice daily, 6 days per week for 12 weeks at 20°C with triplicate groups (6 fish/group) per dietary treatment. There were not significant differences in the final body weight and percent weight gain of fish among dietary groups tested. Feed efficiency of fish fed the 55% crude protein diets was higher than that of fish fed the 45% protein diets (not always significant). Feed efficiency and protein efficiency ratio increased with increasing lipid in the diets with 55% crude protein. However, the lipid did not apparently improve these parameters in the 45% protein diets. Blood triglyceride content of the cultured fish increased with the increase of dietary lipid level, while the other hematological and plasmological parameters were not affected seriously by the dietary composition. Hepato-somatic index tended to increase in accordance with increasing dietary lipid. Similar trend was shown in the crude lipid content of the digestive tract. Crude lipid contents of the eye-side dorsal muscle and the liver of fish fed the diet with the highest lipid content were significantly higher than those in the other dietary groups.View full abstractDownload PDF (1106K) -
Shusaku TAKAGI, Sadao SHIMENO, Hidetsuyo HOSOKAWA, Masaharu UKAWA2000 Volume 48 Issue 3 Pages 545-552
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSThe replacement of fish meal (FM) by combined inclusion of soybean meal (SBM), corn gluten meal (CGM) and poultry by-product meal (PBM) in yearling red sea bream, Pagrus major diet was investigated.
Yearing fish weighing 260g on average were fed for 195 days with the test diets containing 0-39%SBM, 24%SBM with 10-20%CGM or 13-26%PBM, 24%SBM and 10-20%CGM with 13-26%PBM substitute for FM, respectively.
Palatability of test diets was not affected by dietary treatments, but the feeding activity of non-FM deit group decreased with elapse in the rearing period. The growth performance was not affected by dietary inclusion of up to 39%SBM (replacing of 50%FM), but feed conversion decreased slightly with an increase of dietary SBM content. The performance with feed conversion were most excellent in the diets containing 24%SBM with 10%CGM or 13%PBM (replacing of 50%FM), and were similar in diet containing 24%SBM and 10%CGM with 13%PBM (replacing of 90%FM) compared to that of control diet.
These results indicate that FM in yearing red sea bream diet could be replaced 90% by combined inclusion of 24%SBM and 10%CGM with 26%PBM without supplementation of essential amino acids. It is suggested that combined inclusion of alternative protein sources was more effective and economical for the replacement of FM than single inclusion of one of them in diet.View full abstractDownload PDF (1339K) -
Munenori MIYAKAWA, Yoshio TAKEUCHI, Sakiko KAWAHARA, Ryuji UENO2000 Volume 48 Issue 3 Pages 553-557
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSIn previous papers, the simplified methods for detection of the residual antibacterial drugs such as oxytetracycline, oxolinic acid and miloxacin (MLX) in Japanese cultured eel were reported by using bioassay. However, the method showed low detection limits for the drugs (0.2-0.3, μg/g). In this study, further attempt was made to develop more sensitive method by high-performance liquid chromatography (HPLC). The experiment for oral administration was carried out by actural feeding in eel pond. Then, the muscle level of three drugs after dosing was determined by our developed HPLC method. Each drug could be determined at the level of 0.03-0.05, μg/g. N4 -Acetyl form of famonomethoxine and the demethoxy form of MLX, which are the predominant metabolites of drugs in fish, were also determined by using the same column and the mobile phase as we used for the parent drugs. In conclusion, the present method was reliable and convenient, and very useful in order to correct the defect of the simplified bioassay. Furthermore, the method was practical for local food or fish inspector to do on-the-spot inspection.View full abstractDownload PDF (711K) -
Masaaki KASHIWAGI, Akiko SATO, Eitaro BANDO, Motoi YOSHIOKA, Ryuji UEN ...2000 Volume 48 Issue 3 Pages 559-564
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSAmong several electrolyzed NaCI solutions, there are three types such as strong acid (<pH 2.7), weak acid (pH 5-7), and weak alkaline (pH 7-9), which have strong bactericidal activities. We examined physicalchemical and preservative properties of the three type solutions and compared each other to seek for possible candidates for application in aquaculture fields. All solutions were prepared with an electrolyzed water generator without a diaphragm. Characteristics of the solutions just after preparation are: strong acidic type (pH: 2.4, oxidation-reduction potential: +1170 mV, residual chlorine: 15.0 mg/l), weak acidic type (5.6, +995 mV, 12.5 mg/l), and weak alkaline type (8.2, +730 mV, 17.0 mg/l). In preservative test, the solutions in stoppered bottles were kept in a dark room at 20°C and 5°C, respectively. The bactericidal activities were measured by a commercial test paper for living bacteria. As time passed, the bactericidal activities of the all three types dropped remarkably at both 20°C and 5°C, corresponding to decrease in residual chlorine. However, the activity decline was slower in the alkaline type than in other types. From our results, we concluded that the weak alkaline solution is suitable for application in aquaculture fields.View full abstractDownload PDF (915K) -
Masaaki KASHIWAGI, Yuka MAEKAWA, Hiromi TANAKA, Motoi YOSHIOKA, Ryuji ...2000 Volume 48 Issue 3 Pages 565-569
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSWe extended our investigations on fungicidal effect of weak alkaline electrolyzed solution, using Saprolegnia parasitica Coker, one of the most well known pathogens of water mould disease (saprolegniasis) in freshwater fishes. The alkaline solution (pH 8.2, residual chlorine 30 mg/l) was prepared by a generator without a diaphragm. Fungicidal effect was measured by zoospore germination inhibition and mycelial growth inhibition of the pathogen. The zoospore germination was completely inhibited with either 10 s treatment at the residual chlorine concentration of 7.5 mg/l, or 1 min treatment at 2.5 and 5.0 mg/l, respectively. The mycelial growth was also completely inhibited with 60 min treatment at 30 mg/l. These results indicated that the weak alkaline electrolyzed solution have a strong fungicidal effect.View full abstractDownload PDF (2578K) -
Akio TSUJIMURA2000 Volume 48 Issue 3 Pages 571-577
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSTruncation selection of body weight was performed to esitmate the selection response in Ayu Plecoglossus altivelis. Truncation selection had been carried out until the 4th generation to a large selected line and until the 3rd generation to a small selected line. In the 3rd generation, the body weight of the large selected line was 1.49 times larger than that of the non-selected line, and the body weight of the small selected line was 0.51 times smaller than that of the non-selected line.
The average realized heritability, which was dertermined by the ratio of the body weight of the large and small selected lines to the non-selected line in each generation, was 0.370 in the large selected line and 0.580 in the small selected line.
In several rearing experiments, the large selected line showed better performance in body weight than other lines in the 3rd generation. These results suggest that truncation selection is effective to improve growth performance in Ayu.View full abstractDownload PDF (956K) -
Toshihiro YAMAMOTO, Noritaka MOCHIOKA, Akinobu NAKAZONO2000 Volume 48 Issue 3 Pages 579-580
Published: September 20, 2000
Released on J-STAGE: October 28, 2010
JOURNAL FREE ACCESSShort finned-eel Anguilla bicolor pacifica glass-eels are reported to immigrate to Yakushima Island, Japan. This is a significant range extension of short-finned anguillid species.View full abstractDownload PDF (2960K)
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